Detection of Local and Long-Range Transported Aerosol Intrusions Over Cluj-Napoca, Romania Using Multiwavelength Lidar Measurements in Spring 2022

Abstract

It is well known that atmospheric aerosols have both a direct and an indirect impact on the Earth's systems and have natural or anthropogenic origins. In this paper we present the results of the 2022 spring-time lidar measurements conducted within the European Aerosol Research Lidar Network (EARLINET) using a multi-wavelength Raman and depolarization LIDAR system operated in Cluj-Napoca, Romania. The Cluj-Napoca lidar system (CLOP) emission is based on a Nd-YAG laser Continuum INLITE II-30, which has a repetition rate of 30 Hz. The radiation at 1064, 532, and 355 nm is simultaneously emitted into atmosphere. The backscattered radiation is collected by a Cassegrain type telescope with a focal length of 1500 mm. The signal detection unit has a total of 6 detection channels, 4 channels for the elastically backscattered radiation at 1064, 532 (cross and parallel), and 355 nm and 2 channels for the Raman radiation backscattered by nitrogen molecules at 607 and 387 nm. This type of system meets the requirements of the EARLINET network and is suitable to provide reliable data on optical parameters for aerosol characterization. The reference period for the observations was in accordance with EARLINET�s fixed measurements schedule. The preliminary results indicated the presence of both natural (mineral dust) and anthropogenic (resulted from seasonal biomass burning) aerosols originated from local sources or subject of long-range transport (LRT).

Variation of Aerosol Optical Properties and Trends over Cluj-Napoca, Romania, Based on 10 Years of AERONET Data and Satellite-Based Observations

“…Similar to specific events that were highlighted in previous studies on dust intrusions over Cluj-Napoca [65], [67], [68], [73], this statistical analysis confirm that dust aerosols are notably prevalent during the months of April, May, and June. This seasonality is mostly determined by atmospheric circulation patterns.…”

“…On the opposite, higher precipitation values in the colder months played a dominant role in below-cloud aerosol wet deposition. Also, the behavior of the population in Eastern Europe plays a role in contributing to the total aerosol load in the atmosphere in the cold season by generating controlled fires (biomass burnings) in agricultural regions [65]. The majority of these fires occur during the pre-spring (February) and late autumn (November) periods.…”

“…The April minimum can be mainly attributed to the presence of larger aerosol particles such as mineral dust. This might be a consequence of the Saharan dust intrusion events [65]- [68]. Single Scattering Albedo at 440 nm is presented in Figure 7.…”

Variation of Aerosol Optical Properties over Cluj-Napoca, Romania, Based on 10 Years of AERONET Data and MODIS MAIAC AOD Product

“…On the other hand, higher precipitation values in the colder months played a dominant role in below-cloud aerosol wet deposition. In addition, the behavior of the population in Eastern Europe plays a role in contributing to the total aerosol load in the atmosphere in the cold season, through generating controlled fires (biomass burnings) in agricultural regions [63]. The majority of these fires occur during the pre-spring (February) and late autumn (November) periods.…”

“…The April minimum can be mainly attributed to the presence of larger aerosol particles such as mineral dust. This is a consequence of the Saharan dust intrusion events, as shown in [39,[63][64][65].…”